Decoherence due to contacts in ballistic nanostructures

Abstract

memoryless on time scales coarsened over their energy-relaxation time, and the evolution of the current- limiting active region can be considered Markovian. Therefore, we first derive a general Markovian map in the presence of a memoryless environment by coarse graining the exact short-time non-Markovian dynamics of an abstract open system over the environment memory-loss time, and we give the requirements for the validity of this map. We then introduce a model contact-active region interaction that describes carrier injection from the contacts for a generic two-terminal ballistic nanostructure. Starting from this model interaction and using the Markovian dynamics derived by coarse graining over the effective memory-loss time of the contacts, we derive the formulas for the nonequilibrium steady-state distribution functions of the forward- and backward- propagating states in the nanostructure's active region. On the example of a double-barrier tunneling structure, the present approach yields an I-V curve that shows all the prominent resonant features. We address the relationship between the present approach and the Landauer-Buttiker formalism and also briefly discuss the inclusion of scattering.